In the drilling and completion industry, the formation of boreholes for the purpose of production or injection of fluid is common. The boreholes are used for exploration or extraction of natural resources such as hydrocarbons, oil, gas, water, and alternatively for CO2 sequestration.
Tubular system operators employ methods and devices to permit actuation of tubular tools for use within the boreholes. Temporary or permanent plugging device against which to build pressure to cause an actuation are commonly employed. Sometimes actuating is desirable at a first location, and subsequently at a second location. Moreover, additional actuating locations may also be desired and the actuation can be sequential for the locations or otherwise. Systems employing droppable members, such as balls, for example, are typically used for just such purpose. The ball is dropped to a ball seat positioned at the desired location within the borehole thereby creating the desired plug to facilitate the actuation. When running a tubular actuation apparatus in unconventional reservoirs, a single entry sleeve utilizes one activation device (such as a ball) to open the sleeve so that the zone can be stimulated. For example, a ball can be dropped from surface, land on a landing seat within the sleeve, and pressure applied uphole of the ball will move the sleeve in a downhole direction revealing ports in an outer housing of the apparatus.
In applications where the first location is further from surface than the second location, it is common to employ seats with sequentially smaller diameters at locations further from the surface. Dropping balls having sequentially larger diameters allows the ball seat furthest from surface to be plugged first (by a ball whose diameter is complementary to that seat), followed by the ball seat second furthest from surface (by a ball whose diameter is complementary to that seat) and so on. The foregoing system, however, creates increasingly restrictive dimensions within the borehole that may negatively impact flow therethrough as well as limit the size of tools that can be run into the borehole.
The art would be receptive to improved devices and methods for allowing operators to increase the number of actuable locations within a borehole without unduly restricting the inner diameter of the tool over the length of a string.